Pambuka Semaphore ing Linux

Terjemahan artikel disiapake ing wayah wengi wiwitan kursus "Administrator Linux.Basic".

Semaphore minangka mekanisme sing ngidini pangolahan lan utas saingan kanggo nuduhake sumber daya lan mbantu ngatasi macem-macem masalah sinkronisasi kayata balapan, deadlocks (kunci bebarengan), lan benang sing salah laku.

Kanggo ngatasi masalah kasebut, kernel nyedhiyakake alat kayata mutex, semaphore, sinyal, lan alangan.

Ana telung jinis semaphore:

1. Semaphore biner
2. Semaphore-counters (ngetung semafor)
3. Array saka semaphore (set semaphore)

Ndeleng Status IPC

Printah ing ngisor iki nyedhiyakake informasi babagan kahanan saiki komunikasi antar-proses (IPC).

# ipcs
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 65536 root 600 393216 2 dest
0x00000000 98305 root 600 393216 2 dest
0x00000000 131074 root 600 393216 2 dest
0x00000000 163843 root 600 393216 2 dest
0x00000000 196612 root 600 393216 2 dest
0x00000000 229381 root 600 393216 2 dest
0x00000000 262150 root 600 393216 2 dest
0x00000000 294919 root 600 393216 2 dest
0x00000000 327688 root 600 393216 2 dest
------ Semaphore Arrays --------

key semid owner perms nsems

------ Message Queues --------
key msqid owner perms used-bytes messages

Array semaphore aktif

Nampilake informasi babagan susunan semafor sing aktif.

# ipcs -s
------ Semaphore Arrays --------
key semid owner perms nsems

Segmen memori sing dienggo bareng

Deleng informasi babagan segmen memori sing dienggo bareng sing aktif.

# ipcs -m
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 65536 root 600 393216 2 dest
0x00000000 98305 root 600 393216 2 dest

Watesan

tim ipcs -l nampilake memori bareng, semaphore, lan watesan pesen.

# ipcs -l
------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 4194303
max total shared memory (kbytes) = 1073741824
min seg size (bytes) = 1

------ Semaphore Limits --------
max number of arrays = 128
max semaphores per array = 250
max semaphores system wide = 32000
max ops per semop call = 32
semaphore max value = 32767

------ Messages: Limits --------
max queues system wide = 16
max size of message (bytes) = 65536
default max size of queue (bytes) = 65536

Memori sing dienggo bareng

Printah ing ngisor iki nampilake memori sing dienggo bareng.

# ipcs -m
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 65536 root 600 393216 2 dest
0x00000000 98305 root 600 393216 2 dest
0x00000000 131074 root 600 393216 2 dest
0x00000000 163843 root 600 393216 2 dest
0x00000000 196612 root 600 393216 2 dest
0x00000000 229381 root 600 393216 2 dest
0x00000000 262150 root 600 393216 2 dest
0x00000000 294919 root 600 393216 2 dest
0x00000000 327688 root 600 393216 2 dest

Pangripta Sumber Daya

Printah kasebut nampilake pangguna lan klompok pemilik lan panyipta sumber daya.

# ipcs -m -c

------ Shared Memory Segment Creators/Owners --------
shmid perms cuid cgid uid gid
65536 600 root root root root
98305 600 root root root root
131074 600 root root root root
163843 600 root root root root
196612 600 root root root root
229381 600 root root root root
262150 600 root root root root
294919 600 root root root root
327688 600 root root root root

Nggunakake alat IPC

Ing conto ing ngisor iki, parameter -u nampilake ringkesan panggunaan kabeh piranti IPC.

# ipcs -u

------ Shared Memory Status --------
segments allocated 9
pages allocated 864
pages resident 477
pages swapped 0
Swap performance: 0 attempts 0 successes

------ Semaphore Status --------
used arrays = 0
allocated semaphores = 0

------ Messages: Status --------
allocated queues = 0
used headers = 0
used space = 0 bytes

Nalika layanan mandheg, semaphore lan bagean memori sing dienggo bareng uga kudu dibusak. Yen ora dibusak, iki bisa ditindakake kanthi nggunakake printah ipcrm, ngliwati pengenal obyek IPC.

# ipcs -a
# ipcrm -s < sem id>

Sampeyan uga bisa ngganti watesan semaphore nggunakake sysctl.

# /sbin/sysctl -w kernel.sem=250

Source: www.habr.com